Many of the larger tractors in use today have cabs in which the operator sits, these cabs being completely enclosed and often air conditioned. Such cabs are provided with one or more doors which are normally closed during operation. Sometimes, however, when the tractor is being operated without air conditioning, it is desirable for having some means for holding the doors open so as to provide adequate ventilation within the cab. There are numerous other instances in which it is desired to hold the cab door in open position. For example, where the wind is blowing rather strongly and the tractor is stationary, it may still be desirable to have the door open during maintenance so as to provide ready access to the interior of the cab. Various arrangements have been proposed for holding the cab door open. It is desirable that such arrangements provide for more or less automatic latching of the cab door when it is moved to a predetermined position. Furthermore, in order to obtain as much mechanical advantage as possible, it is desirable that the cab door be retained near its outer edge. In some cases, the latch has been nothing more than a means movable to extend over the edge of the door when the door is in its open position. In some such prior devices, it has been necessary for the operator to exert considerable effort to move the latch into latching engagement with the door. Furthermore, the problem of unlatching the door under such conditions becomes more bothersome. It is obviously desirable that the latch be readily released without the operator going to much extra effort.
Some latching arrangements that have been provided have had the drawback that they were in the way of the operator during his normal ingress into or egress out of the cab.
It is obviously desirable that the latch be in a position where it not only firmly retains the cab door in the desired open position but also where it is relatively out of the way of the operator during his normal movement into and out of the cab.
In other cases, friction elements such as wedge elements of resilient material have been employed. These have the drawback that they not only are not positive enough in their action but are also open to the drawback that wear tends to reduce their effectiveness.